Lipid profile test or lipid panel or cholesterol test is a panel of blood tests that are used to detect abnormal levels of various types of lipids present in the body.

It is performed to check for any risk of coronary heart disease especially in the presence of risk factors such as sedentary lifestyle, consumption of high calorie-food, stress or family history of heart disease.

Diet and lifestyle changes are recommended and medicines may be prescribed to lower cholesterol levels. Statins are the most common medicine to be prescribed to lower cholesterol.

What are Lipids?

Lipids are the fats and fatty substances that are present in the blood and body tissues.

They are synthesized in the body using complex biosynthetic pathways. Some lipids are considered essential and need to be supplemented in the diet.

Much of the cholesterol is located in cell membranes. It also occurs in blood in free form as plasma lipoproteins. Lipoproteins are complex aggregates of lipids and proteins that allow the lipids to travel in a watery or aqueous solution, thus enabling their transport throughout the body.

Functions of Lipids in the Body

They are used by the body as a source of energy.

Lipids form an important component of cell membranes.

They act as chemical messengers to send information between organelles and cells. Present on the cell membranes, they can act as receptors and membrane anchors for proteins and can modify the structure and function of cells.

Subcutaneous fat under the skin helps in insulation, protection from cold, and maintenance of body temperature.

Some lipids like fat-soluble vitamins (A, D, E, and K) are essential nutrients.

They protect delicate internal organs from traumatic injuries and shock.

Many hormones like estrogens, androgens, and cortisol, are formed from cholesterol.

They play an important role in nervous system structure and function. They form an essential component of synaptic complexes and myelin in the brain and thus participate in multiple signaling pathways.

Bile salts which are the by-products of cholesterol help in the digestion and absorption of fat and fat-soluble vitamins.

Sources of Cholesterol in the Body

Cholesterol that is needed for the proper functioning of the body is produced in the liver. A significant portion of cholesterol also comes from diet. Exogenous sources of cholesterol include milk, butter, eggs, and meat.

Effects of Abnormal Lipid Levels

Although lipids are required for normal functioning of the body, their high levels can lead to life-threatening conditions.

The extra cholesterol may be deposited as plaques in the walls of blood vessels. Plaques can narrow or ultimately block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis). Atherosclerosis can further lead to a number of health problems, including coronary artery disease, cardiovascular diseases, heart attacks, and stroke.

To evaluate the effect of lipid-lowering drug treatments or lifestyle modifications

Lipid profile is also done as a part of a routine health examination.

When and How Frequently Should Lipid Profile Test be Done?

The American Academy of Family Physicians (AAFP) recommends that:

Healthy adult men should get their first lipid panel test by age 35.

Healthy adult women should have their first test at age 45.

Testing should be carried out earlier in adults if they have certain diseases (diabetes, high blood pressure, heart disease, stroke, etc) or a family history of these diseases.

There is not enough evidence of the benefits of lipid profile testing in children and adolescents 20 years or younger.

If the test results are normal, lipid profile testing should be repeated again every five years.

If a person is taking cholesterol-lowering medicines or has any of the diseases or risk factors mentioned above, lipid testing should be carried out once a year.

How to Prepare for Lipid Profile Test?

Lipid profile test requires fasting

Fasting blood sample should be collected in the morning after a minimum of 12-14 hour overnight fasting. Water can be consumed during this period. However, beverages like tea, coffee, milk, juice, etc or any other food should not be taken in the morning until the blood sample is collected.

In the case of diabetics on oral or injectable medicines, it is important to consult the treating physician about continuing with the medication prior to specimen collection.

High-fat foods or alcohol should not be consumed the night before the test. Also one should not do heavy exercise just before the test.

In case of heart attack, surgery, infection, injury or pregnancy, it is advisable to wait for at least two months before getting a lipid profile test so as to get accurate results.

What Does a Lipid Profile Test Measure?

A lipid profile measures different types of lipids, or fats present in the blood.

Total cholesterol

It measures the total amount of cholesterol present in the blood.

Cholesterol is a type of fat, which is both produced by the body as well as consumed in the diet through animal products.

Cholesterol is one of the major constituents of all the cell membranes in the body. It is also required for making hormones, fat-soluble vitamins, and bile acids. However, excess of cholesterol can get deposited in blood vessels or other organs and lead to coronary artery disease.

The level of cholesterol present in the body depends on the food consumed, the ability of the body to metabolize it and genetic factors.

Triglycerides

It measures the triglycerides present in all the lipoprotein particles. The majority of the triglycerides are present in the very low-density lipoproteins (VLDL).

Triglycerides are the most abundant type of lipid present in the diet. Also, the excess calories consumed are converted into triglycerides by the body. These triglycerides are stored in the fat cells. This is the method by which the body stores energy.

People who are obese, overweight, diabetic or those who consume an excess of sweets or alcohol usually have a high level of triglycerides. People suffering from an underactive thyroid, liver disease, nephrotic syndrome ( kidney disease) or genetic condition may also have a high level of triglycerides. Hormone replacement medicines can also increase the levels of triglycerides.

High levels of triglycerides are linked with an increased risk of blood vessel and heart disease.

High-density lipoprotein (HDL) cholesterol

It measures the amount of cholesterol present in HDL particles.

HDL is a lipoprotein (a combination of fat and protein) found in the blood. It is called “good” cholesterol because it carries excess cholesterol from blood and other parts of the body to the liver. The liver then removes this cholesterol from the body.

A high level of HDL lowers the risk of blood vessel and heart disease.

Low-density lipoprotein (LDL) cholesterol

It calculates or measures the amount of cholesterol present in LDL particles.

LDL is also a lipoprotein found in the blood. It is called “bad cholesterol” because it picks up excess cholesterol from the blood and takes it to the cells. It causes the deposition of cholesterol in walls of blood vessels, leading to atherosclerosis, coronary artery disease, heart attack, stroke, and death.

Lowering blood levels of LDL is one of the main objectives of cholesterol-lowering treatment.

Very low-density lipoprotein cholesterol (VLDL-C)

The difference between VLDL and LDL lies in the different percentages of the cholesterol, protein, and triglycerides that constitute each of these lipoproteins. VLDL contains more triglycerides while LDL contains more of cholesterol.

VLDL is synthesized in the liver. Its main function is to carry lipids (mainly triglycerides) from the liver to various parts of the body.

Both VLDL and LDL are considered types of “bad cholesterol”.

Normal values of Lipid Profile

Cholesterol

< 200 mg/dl

Triglycerides

<150 mg/dl

HDL

40-60 mg/dl

LDL

<129 mg/dl

VLDL

<30 mg/dl

ATP III Classification for LDL, Total and HDL Cholesterol, and Triglyceride Values

What to do in case of high or abnormal lipid levels?

It is important to maintain a healthy level of lipids in the body to stay healthy. Although the body produces cholesterol that is needed for the proper functioning of the body, a significant portion of cholesterol comes from diet. Eating too much of foods that are high in saturated fats and trans unsaturated fats (trans fats) or having a genetic predisposition can cause abnormal levels of lipids in the body.

High cholesterol can be treated with lifestyle changes and medication. Lowering high levels of LDL in the blood can help avoid heart and blood vessel-related diseases.

How to lower lipid levels?

Lifestyle changes including regular exercise

Consume a balanced diet. Eat a wide variety of vegetables, fruits, whole-grain products, low-fat dairy products, and lean sources of protein. A dietician may be consulted for advice in making dietary changes. Only 7 percent of the daily calories should come from saturated fat. One should aim to consume less than 200 mg of cholesterol from food each day.

In the case of obesity, reduce weight by dietary changes and exercise. Avoid foods rich in calories and fats

Limit alcohol consumption

Quit smoking

Avoid high sodium foods

Control high blood pressure or diabetes

If lifestyle changes and dietary modifications alone are unable to control the high lipid levels in the body, the following medicines may be given.

Statins: They are the most effective and commonly used lipid-lowering drugs. An example is an atorvastatin.

Besides, the following drugs have also proved to be beneficial in case of high lipid levels:

Niacin

Fibrates

Zetia

Bile acid sequestrants

References

National Cholesterol Education Program Expert Panel: Third Report of The National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III): final report. Circulation. 2002; 106:3143–342.